Spinning devices are used primarily for the manufacture of endless filaments, which in the first instance emerge from the spinning holes, spinning orifices or spinning nozzles, and are then in particular deposited so as to form spunbond nonwoven materials. A spinning plate may have several thousand spinning apertures. The term “spinning device” relates within the framework of the invention to the most widely differing spinning processes. In this context, “spinning devices” may even mean, for example, melt-blown filament blowing heads.
With the spinning devices known from practice, as a rule a filter is arranged upstream of the spinning plate, which catches inhomogeneities in the melts introduced. After prolonged operation of the spinning device, parts of this filter may become clogged and/or some of the spinning apertures or capillaries may be contaminated by impurities. If the impurities and/or clogging are serious, the spinning plate must be dismantled and cleaned, and, if necessary, refitted with a new filter. However, if only a few spinning apertures or spinning capillaries are contaminated or impaired in their function due to impurities in the filter, it is more economical for the spinning apertures which are no longer functioning properly to be temporarily closed off by closure elements or by plugs. Only when the dirt contamination increases, or if a considerable number of apertures can no longer be used properly, is the spinning plate dismantled for the purpose of cleaning. Cleaning is carried out as a rule by means of a pyrolysis treatment, in which, with underpressure and/or inert conditions, the plastic residue and impurities adhering to the spinning plate are gasified. Subsequent cleaning can be carried out in ultrasound baths and/or with high-pressure cleaners. By means of the latter treatment measures residual ash in particular can be removed.
With the method known from practice, the clogged spinning apertures, or those impeded in their function, are temporarily closed of with closure elements in the form of graphite plugs. These graphite plugs are produced from a graphite/clay mixture. The graphite is accordingly likewise present in these graphite plugs in a fired ceramic bond. The ceramic bond is thermally stable up to temperatures in excess of 1000° C. During later cleaning of the spinning device or the spinning plate, these graphite plugs must be removed in their entirety, in order for all the spinning apertures to be fully functional as in the original condition of the spinning plate.
The removal of the graphite plugs within the framework of the cleaning measures known from practice, with conventional spinning apertures, is easily possible in the form of round capillaries with diameters of, for example, 0.4 to 1 mm. If problems nevertheless arise, it is possible, within the framework of these known measures to carry out an additional mechanical cleaning, for example with a wire or the like. This has the disadvantage, however, that with spinning apertures with small diameters there is a risk of damage to the spinning apertures. This applies in particular, however, to spinning apertures with special outlet cross-sections, such as spinning apertures for hollow fibers and the like. These outlet apertures frequently have gap widths of less than 0.4 mm. A mechanical cleaning, such as with a wire, for example, without damage to the spinning apertures is difficult or impossible.